Dementia with Lewy bodies (DLB) is a neurodegenerative disorder clinically characterized by dementia and parkinsonism, often with fluctuating cognitive function, visual hallucinations, falls, syncopal episodes, and sensitivity to neuroleptic medication. Pathologically, Lewy bodies are present in a pattern more widespread than usually observed in Parkinson disease (see PD; 168600). Alzheimer disease (AD; 104300)-associated pathology and spongiform changes may also be seen (McKeith et al., 1996; Mizutani, 2000; McKeith et al., 2005).